In order to meet the demand for wireless data traffic soaring since the fourth-generation (4G) communication system came to the market, there are ongoing efforts to develop enhanced fifth-generation (5G) communication systems or pre-5G communication systems. For the reasons, the 5G communication system or pre-5G communication system is called the beyond 4G network communication system or post long-term evolution (LTE) system.
For higher data transmit rates, 5G communication systems are considered to be implemented on ultra high frequency bands (mmWave), such as, e.g., a 60 GHz band. To mitigate path loss on the ultra-high frequency band and increase the reach of radio waves, the following techniques are taken into account for the 5G communication system: beamforming, massive multi-input multi-output (MIMO), full dimensional MIMO (FD-MIMO), array antenna, analog beamforming, and large scale antenna.
Also being developed are various technologies for the 5G communication system to have an enhanced network, such as evolved or advanced small cell, cloud radio access network (cloud RAN), ultra-dense network, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, coordinated multi-point (CoMP), and interference cancellation.
Other techniques being developed for 5G system are among hybrid frequency shift keying (FSK) and quadrature amplitude modulation (QAM) (FQAM) and sliding window superposition coding (SWSC), as advanced coding modulation (ACM) schemes, and filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA), as advanced access techniques.
D2D discovery is the technology in which a user equipment (UE) capable of D2D communication (hereinafter, denoted a “D2D-capable UE”) determines whether other D2D-capable UEs are in proximity. Discovering a D2D-capable UE is to determine whether there are another UEs capable of D2D communication using a D2D discovery method. in cases where proximity needs to be known by one or more verified applications of a D2D-capable UE performing a discovery operation in the D2D-capable UE, the D2D-capable UE performing the discovery operation becomes of interest.
For example, a social networking application may be activated to use a D2D discovery function. D2D discovery is performed by activating the D2D-capable UE of the user of a predetermined social networking application, and discovery may be done by the D2D-capable UEs of the friends of the user. As another example, may activate the D2D-capable UE of the user of a predetermined discovery application in order to search for nearby shops/restaurants. A D2D-capable UE may search for nearby other D2D-capable UEs using direct UE-to-UE signaling.
Meanwhile, discovery messages used for a D2D discovery operation are generally transmitted through a physical sidelink discovery channel (PSDCH). However, the PSDCH is subject to the limitation that it can transmit only discovery messages with a fixed size. Further, the PSDCH is unavailable for new messages for inter-vehicle communication or messages for public safety requiring periodic transmission in variable sizes.
Therefore, a need exists for a scheme capable of effective transmission regardless of the size of messages to be transmitted. Also required is a scheme allowing a UE to send discovery messages distinctively from normal data so that the discovery messages may be easily detected on the receive side.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determinations have been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.